作业帮化简求值:3a²b-[2ab²-2(-a²b+4ab²)]-5ab²,其中a=-2,b=½
来源：学生作业帮助网 编辑：作业帮 时间：2024/11/24 01:47:44
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化简求值:3a²b-[2ab²-2(-a²b+4ab²)]-5ab²,其中a=-2,b=½
化简求值:3a²b-[2ab²-2(-a²b+4ab²)]-5ab²,其中a=-2,b=½
化简求值:3a²b-[2ab²-2(-a²b+4ab²)]-5ab²,其中a=-2,b=½
3a²b-[2ab²-2(-a²b+4ab²)]-5ab²
=3a²b-[2ab²+2a²b-8ab²]-5ab²
=3a²b-2ab²-2a²b+8ab²-5ab²
=3a²b-2a²b-2ab²+8ab²-5ab²
=a²b+ab²
=ab（a+b）
a=-2,b=½,
原式=-2*1/2*(-2+1/2)=-(-3/2)=3/2
3a²b-[2ab²-2(-a²b+4ab²)]-5ab²
=3a²b-[2ab²+2a²b-8ab²]-5ab²
=3a²b-2a²b+6ab²-5ab²
=a²b+ab²
当a=-2,b=½时
原式=(-2)²×½-2×(½)²=1.5
解
原式
=3a²b-(2ab²+2a²b-8ab²)-5ab²
=3a²b-(2a²b-6ab²)-5ab²
=(3a²b-2a²b)+(6ab²-5ab²)
=a²b+ab²
=ab(a+b)
=-2×(1/2)(-2+1/2)
=-(-3/2)
=3/2